Brake lights, directional signals, and emergency lights are found on most automobiles; aircraft have flashing indicator or signal lights; and boats, in turn, have signal lights which indicate directional or emergency signals to others. In most cases the existing lights, consisting of a conventional electric bulb within an exterior partially protective housing, are most satisfactory, but under certain conditions, particularly where exposure to excessive moisture or water is encountered, such signal lights can indeed fail. As an obvious example, trailers for carrying boats require signal lights for signaling to following vehicles but are periodically exposed to an underwater condition when a boat carried thereby is to be launched, or alternatively is to be removed from the water, and consequent electrical failure constitutes a common experience.